This invention relates to antibiotic compositions suitable for pharmaceutical use. More particularly, it relates to magnesium-calcium-oxytetracycline mixed chelates in aqueous 2-pyrrolidone solution.
U.S. Pat. No. 4,018,899 discloses oxytetracycline aqueous solutions containing 2-pyrrolidone as a cosolvent. The oxytetracycline is present as a magnesium chelate.
U.S. Pat. No. 3,017,323 discloses oxytetracycline in aqueous glycol solutions containing calcium and magnesium. A ratio of 1:1:3 of calcium:magnesium:oxytetracycline is employed.
U.S. Pat. No. 3,929,989 discloses suspensions of a calcium-magnesium-oxytetracycline complex having a molar ratio of combined calcium and magnesium to oxytetracycline of about 4 to 1 in aqueous 1,2-propanediol.